In this article, we report the case of a 16-month-old German boy who was admitted to the Children's Hospital of Stuttgart with a 4-week history of intermittent fever, decreased appetite, weakness, fatigue, and difficulty sleeping. He was healthy at birth and remained so for the first 15 months of his life. On admission, physical examination showed enlarged cervical, axillary, and inguinal lymph nodes, as well as hepatosplenomegaly. Laboratory data revealed pancytopenia, elevated liver function tests, and hypergammaglobulinemia. Blood, stool, and urine culture results were negative. Viral infections and rheumatologic and autoimmune disorders were ruled out, but a positive titer for Leishmania antibodies was noted. In a liver and bone marrow biopsy, the amastigote form of the parasite could not be seen in cells. The promastigote form of Leishmania was found and the diagnosis of visceral leishmaniasis was made by combining the cultures of both the liver and the bone marrow biopsy material in 5 mL 0.9% saline on brain heart infusion agar, supplemented with defibrinated rabbit blood and incubated at 25 to 26 degrees C for 5 days. The parasite was identified by Southern blot analysis as Leishmania infantum. Specific therapy with the antimonial compound sodium stibogluconate with a dose of 20 mg/kg body weight was begun immediately. Within 4 days, the patient became afebrile. The side effects of treatment, including erosive gastritis, cholelithiasis, worsening hepatosplenomegaly, elevation of liver enzymes, pancreatitis, and electrocardiogram abnormalities, necessitated the discontinuation of treatment after 17 days. On discharge 4 weeks later, the patient was stabilized and afebrile with a normal spleen, normal complete blood count, normal gammaglobulins, and decreasing antibody titers to Leishmania. During the next 24 months, the patient experienced intermittent episodes of abdominal pain, decreased appetite, recurrent arthralgia, and myalgia. But at his last examination in January 1998, he was well; all symptoms mentioned above had disappeared. Because the child had never left Germany, nonvector transmission was suspected and household contacts were examined. His mother was the only one who had a positive antibody titer against Leishmania donovani complex. She had traveled several times to endemic Mediterranean areas (Portugal, Malta, and Corse) before giving birth to the boy. But she had never been symptomatic for visceral leishmaniasis. Her bone marrow, spleen, and liver biopsy results were within normal limits. Culture results and polymerase chain reaction of this material were negative. A Montenegro skin test result was positive, indicating a previous infection with Leishmania. Western blot analysis showed specific recognition by maternal antibodies of antigens of Leishmania cultured from the boy's tissue. Visceral leishmaniasis is endemic to several tropical and subtropical countries, but also to the Mediterranean region. It is transmitted by the sand fly (Phlebotomus, Lutzomyia). Occasional nonvector transmissi...